To round numbers to the nearest ten thousand, make the numbers whose
last four digits are 0001 through 4999 into the next lower number that
ends in 0000. For example 54,424 rounded to the nearest ten thousand
would be 50,000.

Numbers that have the last four digits of 5000 or more should be
rounded up to the next even ten thousand. The number 78,988 rounded
to the nearest ten thousand would be 80,000.